/*
 * contrib/btree_gist/btree_utils_var.c
 */
#include "postgres.h"
#include "knl/knl_variable.h"

#include "btree_gist.h"

#include <math.h>
#include <limits.h>
#include <float.h>

#include "btree_utils_var.h"
#include "utils/pg_locale.h"
#include "utils/builtins.h"
#include "utils/rel.h"
#include "utils/rel_gs.h"

/* used for key sorting */
typedef struct {
    int i;
    GBT_VARKEY* t;
} Vsrt;

typedef struct {
    const gbtree_vinfo* tinfo;
    Oid collation;
} gbt_vsrt_arg;

PG_FUNCTION_INFO_V1(gbt_var_decompress);
extern "C" Datum gbt_var_decompress(PG_FUNCTION_ARGS);

Datum gbt_var_decompress(PG_FUNCTION_ARGS)
{
    GISTENTRY* entry = (GISTENTRY*)PG_GETARG_POINTER(0);
    GBT_VARKEY* key = (GBT_VARKEY*)DatumGetPointer(PG_DETOAST_DATUM(entry->key));

    if (key != (GBT_VARKEY*)DatumGetPointer(entry->key)) {
        GISTENTRY* retval = (GISTENTRY*)palloc(sizeof(GISTENTRY));

        gistentryinit(*retval, PointerGetDatum(key), entry->rel, entry->page, entry->offset, FALSE);

        PG_RETURN_POINTER(retval);
    }

    PG_RETURN_POINTER(entry);
}

/* Returns a better readable representation of variable key ( sets pointer ) */
GBT_VARKEY_R
gbt_var_key_readable(const GBT_VARKEY* k)
{

    GBT_VARKEY_R r;

    r.lower = (bytea*)&(((char*)k)[VARHDRSZ]);
    if (VARSIZE(k) > (VARHDRSZ + (VARSIZE(r.lower))))
        r.upper = (bytea*)&(((char*)k)[VARHDRSZ + INTALIGN(VARSIZE(r.lower))]);
    else
        r.upper = r.lower;
    return r;
}

GBT_VARKEY* gbt_var_key_copy(const GBT_VARKEY_R* u, bool force_node)
{
    GBT_VARKEY* r = NULL;

    if (u->lower == u->upper && !force_node) { /* leaf key mode */
        r = (GBT_VARKEY*)palloc(VARSIZE(u->lower) + VARHDRSZ);
        memcpy(VARDATA(r), u->lower, VARSIZE(u->lower));
        SET_VARSIZE(r, VARSIZE(u->lower) + VARHDRSZ);
    } else { /* node key mode  */
        r = (GBT_VARKEY*)palloc(INTALIGN(VARSIZE(u->lower)) + VARSIZE(u->upper) + VARHDRSZ);
        memcpy(VARDATA(r), u->lower, VARSIZE(u->lower));
        memcpy(VARDATA(r) + INTALIGN(VARSIZE(u->lower)), u->upper, VARSIZE(u->upper));
        SET_VARSIZE(r, INTALIGN(VARSIZE(u->lower)) + VARSIZE(u->upper) + VARHDRSZ);
    }
    return r;
}

static GBT_VARKEY* gbt_var_leaf2node(GBT_VARKEY* leaf, const gbtree_vinfo* tinfo)
{
    GBT_VARKEY* out = leaf;

    if (tinfo->f_l2n)
        out = (*tinfo->f_l2n)(leaf);

    return out;
}

/*
 * returns the common prefix length of a node key
 */
static int32 gbt_var_node_cp_len(const GBT_VARKEY* node, const gbtree_vinfo* tinfo)
{
    GBT_VARKEY_R r = gbt_var_key_readable(node);
    int32 i = 0;
    int32 l = 0;
    int32 t1len = VARSIZE(r.lower) - VARHDRSZ;
    int32 t2len = VARSIZE(r.upper) - VARHDRSZ;
    int32 ml = Min(t1len, t2len);
    char* p1 = VARDATA(r.lower);
    char* p2 = VARDATA(r.upper);

    if (ml == 0)
        return 0;

    while (i < ml) {
        if (tinfo->eml > 1 && l == 0) {
            if ((l = pg_mblen(p1)) != pg_mblen(p2)) {
                return i;
            }
        }
        if (*p1 != *p2) {
            if (tinfo->eml > 1) {
                return (i - l + 1);
            } else {
                return i;
            }
        }

        p1++;
        p2++;
        l--;
        i++;
    }
    return (ml); /* lower == upper */
}

/*
 * returns true, if query matches prefix ( common prefix )
 */
static bool gbt_bytea_pf_match(const bytea* pf, const bytea* query, const gbtree_vinfo* tinfo)
{
    bool out = FALSE;
    int32 qlen = VARSIZE(query) - VARHDRSZ;
    int32 nlen = VARSIZE(pf) - VARHDRSZ;

    if (nlen <= qlen) {
        char* q = VARDATA(query);
        char* n = VARDATA(pf);

        out = (memcmp(q, n, nlen) == 0);
    }

    return out;
}

/*
 * returns true, if query matches node using common prefix
 */
static bool gbt_var_node_pf_match(const GBT_VARKEY_R* node, const bytea* query, const gbtree_vinfo* tinfo)
{
    return (tinfo->trnc &&
            (gbt_bytea_pf_match(node->lower, query, tinfo) || gbt_bytea_pf_match(node->upper, query, tinfo)));
}

/*
 *  truncates / compresses the node key
 *  cpf_length .. common prefix length
 */
static GBT_VARKEY* gbt_var_node_truncate(const GBT_VARKEY* node, int32 cpf_length, const gbtree_vinfo* tinfo)
{
    GBT_VARKEY* out = NULL;
    GBT_VARKEY_R r = gbt_var_key_readable(node);
    int32 len1 = VARSIZE(r.lower) - VARHDRSZ;
    int32 len2 = VARSIZE(r.upper) - VARHDRSZ;
    int32 si;
    char* out2 = NULL;

    len1 = Min(len1, (cpf_length + 1));
    len2 = Min(len2, (cpf_length + 1));

    si = 2 * VARHDRSZ + INTALIGN(len1 + VARHDRSZ) + len2;
    out = (GBT_VARKEY*)palloc(si);
    SET_VARSIZE(out, si);

    memcpy(VARDATA(out), r.lower, len1 + VARHDRSZ);
    SET_VARSIZE(VARDATA(out), len1 + VARHDRSZ);

    out2 = VARDATA(out) + INTALIGN(len1 + VARHDRSZ);
    memcpy(out2, r.upper, len2 + VARHDRSZ);
    SET_VARSIZE(out2, len2 + VARHDRSZ);

    return out;
}

void gbt_var_bin_union(Datum* u, GBT_VARKEY* e, Oid collation, const gbtree_vinfo* tinfo)
{
    GBT_VARKEY_R eo = gbt_var_key_readable(e);
    GBT_VARKEY_R nr;

    if (eo.lower == eo.upper) /* leaf */
    {
        GBT_VARKEY* tmp = NULL;

        tmp = gbt_var_leaf2node(e, tinfo);
        if (tmp != e)
            eo = gbt_var_key_readable(tmp);
    }

    if (DatumGetPointer(*u)) {
        GBT_VARKEY_R ro = gbt_var_key_readable((GBT_VARKEY*)DatumGetPointer(*u));
        bool update = false;

        nr.lower = ro.lower;
        nr.upper = ro.upper;

        if ((*tinfo->f_cmp)(ro.lower, eo.lower, collation) > 0) {
            nr.lower = eo.lower;
            update = true;
        }

        if ((*tinfo->f_cmp)(ro.upper, eo.upper, collation) < 0) {
            nr.upper = eo.upper;
            update = true;
        }

        if (update)
            *u = PointerGetDatum(gbt_var_key_copy(&nr, TRUE));
    } else {
        nr.lower = eo.lower;
        nr.upper = eo.upper;
        *u = PointerGetDatum(gbt_var_key_copy(&nr, TRUE));
    }
}

GISTENTRY* gbt_var_compress(GISTENTRY* entry, const gbtree_vinfo* tinfo)
{

    GISTENTRY* retval = NULL;

    if (entry->leafkey) {
        GBT_VARKEY* r = NULL;
        bytea* leaf = (bytea*)DatumGetPointer(PG_DETOAST_DATUM(entry->key));
        GBT_VARKEY_R u;

        u.lower = u.upper = leaf;
        r = gbt_var_key_copy(&u, FALSE);

        retval = (GISTENTRY*)palloc(sizeof(GISTENTRY));
        gistentryinit(*retval, PointerGetDatum(r), entry->rel, entry->page, entry->offset, TRUE);
    } else
        retval = entry;

    return (retval);
}

GBT_VARKEY* gbt_var_union(const GistEntryVector* entryvec, int32* size, Oid collation, const gbtree_vinfo* tinfo)
{

    int i = 0, numranges = entryvec->n;
    GBT_VARKEY* cur = NULL;
    Datum out;
    GBT_VARKEY_R rk;

    *size = sizeof(GBT_VARKEY);

    cur = (GBT_VARKEY*)DatumGetPointer(entryvec->vector[0].key);
    rk = gbt_var_key_readable(cur);
    out = PointerGetDatum(gbt_var_key_copy(&rk, TRUE));

    for (i = 1; i < numranges; i++) {
        cur = (GBT_VARKEY*)DatumGetPointer(entryvec->vector[i].key);
        gbt_var_bin_union(&out, cur, collation, tinfo);
    }

    /* Truncate (=compress) key */
    if (tinfo->trnc) {
        int32 plen;
        GBT_VARKEY* trc = NULL;

        plen = gbt_var_node_cp_len((GBT_VARKEY*)DatumGetPointer(out), tinfo);
        trc = gbt_var_node_truncate((GBT_VARKEY*)DatumGetPointer(out), plen + 1, tinfo);

        out = PointerGetDatum(trc);
    }

    return ((GBT_VARKEY*)DatumGetPointer(out));
}

bool gbt_var_same(Datum d1, Datum d2, Oid collation, const gbtree_vinfo* tinfo)
{
    bool result = false;
    GBT_VARKEY* t1 = (GBT_VARKEY*)DatumGetPointer(d1);
    GBT_VARKEY* t2 = (GBT_VARKEY*)DatumGetPointer(d2);
    GBT_VARKEY_R r1, r2;

    r1 = gbt_var_key_readable(t1);
    r2 = gbt_var_key_readable(t2);

    if (t1 && t2)
        result = ((*tinfo->f_cmp)(r1.lower, r2.lower, collation) == 0 &&
                  (*tinfo->f_cmp)(r1.upper, r2.upper, collation) == 0);
    else
        result = (t1 == NULL && t2 == NULL);

    return result;
}

float* gbt_var_penalty(float* res, const GISTENTRY* o, const GISTENTRY* n, Oid collation, const gbtree_vinfo* tinfo)
{
    GBT_VARKEY* orge = (GBT_VARKEY*)DatumGetPointer(o->key);
    GBT_VARKEY* newe = (GBT_VARKEY*)DatumGetPointer(n->key);
    GBT_VARKEY_R ok, nk;

    *res = 0.0;

    nk = gbt_var_key_readable(newe);
    if (nk.lower == nk.upper) /* leaf */
    {
        GBT_VARKEY* tmp = NULL;

        tmp = gbt_var_leaf2node(newe, tinfo);
        if (tmp != newe)
            nk = gbt_var_key_readable(tmp);
    }
    ok = gbt_var_key_readable(orge);

    if ((VARSIZE(ok.lower) - VARHDRSZ) == 0 && (VARSIZE(ok.upper) - VARHDRSZ) == 0)
        *res = 0.0;
    else if (!(((*tinfo->f_cmp)(nk.lower, ok.lower, collation) >= 0 || gbt_bytea_pf_match(ok.lower, nk.lower, tinfo)) &&
                 ((*tinfo->f_cmp)(nk.upper, ok.upper, collation) <= 0 ||
                     gbt_bytea_pf_match(ok.upper, nk.upper, tinfo)))) {
        Datum d = PointerGetDatum(0);
        double dres;
        int32 ol, ul;

        gbt_var_bin_union(&d, orge, collation, tinfo);
        ol = gbt_var_node_cp_len((GBT_VARKEY*)DatumGetPointer(d), tinfo);
        gbt_var_bin_union(&d, newe, collation, tinfo);
        ul = gbt_var_node_cp_len((GBT_VARKEY*)DatumGetPointer(d), tinfo);

        if (ul < ol) {
            dres = (ol - ul); /* reduction of common prefix len */
        } else {
            GBT_VARKEY_R uk = gbt_var_key_readable((GBT_VARKEY*)DatumGetPointer(d));
            unsigned char tmp[4];

            tmp[0] = (unsigned char)(((VARSIZE(ok.lower) - VARHDRSZ) <= ul) ? 0 : (VARDATA(ok.lower)[ul]));
            tmp[1] = (unsigned char)(((VARSIZE(uk.lower) - VARHDRSZ) <= ul) ? 0 : (VARDATA(uk.lower)[ul]));
            tmp[2] = (unsigned char)(((VARSIZE(ok.upper) - VARHDRSZ) <= ul) ? 0 : (VARDATA(ok.upper)[ul]));
            tmp[3] = (unsigned char)(((VARSIZE(uk.upper) - VARHDRSZ) <= ul) ? 0 : (VARDATA(uk.upper)[ul]));
            dres = Abs(tmp[0] - tmp[1]) + Abs(tmp[3] - tmp[2]);
            dres /= 256.0;
        }

        *res += FLT_MIN;
        *res += (float)(dres / ((double)(ol + 1)));
        *res *= (FLT_MAX / (o->rel->rd_att->natts + 1));
    }

    return res;
}

static int gbt_vsrt_cmp(const void* a, const void* b, void* arg)
{
    GBT_VARKEY_R ar = gbt_var_key_readable(((const Vsrt*)a)->t);
    GBT_VARKEY_R br = gbt_var_key_readable(((const Vsrt*)b)->t);
    const gbt_vsrt_arg* varg = (const gbt_vsrt_arg*)arg;
    int res;

    res = (*varg->tinfo->f_cmp)(ar.lower, br.lower, varg->collation);
    if (res == 0)
        return (*varg->tinfo->f_cmp)(ar.upper, br.upper, varg->collation);

    return res;
}

GIST_SPLITVEC* gbt_var_picksplit(
    const GistEntryVector* entryvec, GIST_SPLITVEC* v, Oid collation, const gbtree_vinfo* tinfo)
{
    OffsetNumber i, maxoff = entryvec->n - 1;
    Vsrt* arr = NULL;
    int svcntr = 0, nbytes;
    char* cur = NULL;
    GBT_VARKEY** sv = NULL;
    gbt_vsrt_arg varg;

    arr = (Vsrt*)palloc((maxoff + 1) * sizeof(Vsrt));
    nbytes = (maxoff + 2) * sizeof(OffsetNumber);
    v->spl_left = (OffsetNumber*)palloc(nbytes);
    v->spl_right = (OffsetNumber*)palloc(nbytes);
    v->spl_ldatum = PointerGetDatum(0);
    v->spl_rdatum = PointerGetDatum(0);
    v->spl_nleft = 0;
    v->spl_nright = 0;

    sv = (GBT_VARKEY**)palloc(sizeof(bytea*) * (maxoff + 1));

    /* Sort entries */

    for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i)) {
        GBT_VARKEY_R ro;

        cur = (char*)DatumGetPointer(entryvec->vector[i].key);
        ro = gbt_var_key_readable((GBT_VARKEY*)cur);
        if (ro.lower == ro.upper) /* leaf */
        {
            sv[svcntr] = gbt_var_leaf2node((GBT_VARKEY*)cur, tinfo);
            arr[i].t = sv[svcntr];
            if (sv[svcntr] != (GBT_VARKEY*)cur)
                svcntr++;
        } else
            arr[i].t = (GBT_VARKEY*)cur;
        arr[i].i = i;
    }

    /* sort */
    varg.tinfo = tinfo;
    varg.collation = collation;
    qsort_arg((void*)&arr[FirstOffsetNumber], maxoff - FirstOffsetNumber + 1, sizeof(Vsrt), gbt_vsrt_cmp, (void*)&varg);

    /* We do simply create two parts */

    for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i)) {
        if (i <= (maxoff - FirstOffsetNumber + 1) / 2) {
            gbt_var_bin_union(&v->spl_ldatum, arr[i].t, collation, tinfo);
            v->spl_left[v->spl_nleft] = arr[i].i;
            v->spl_nleft++;
        } else {
            gbt_var_bin_union(&v->spl_rdatum, arr[i].t, collation, tinfo);
            v->spl_right[v->spl_nright] = arr[i].i;
            v->spl_nright++;
        }
    }

    /* Truncate (=compress) key */
    if (tinfo->trnc) {
        int32 ll = gbt_var_node_cp_len((GBT_VARKEY*)DatumGetPointer(v->spl_ldatum), tinfo);
        int32 lr = gbt_var_node_cp_len((GBT_VARKEY*)DatumGetPointer(v->spl_rdatum), tinfo);
        GBT_VARKEY* dl = NULL;
        GBT_VARKEY* dr = NULL;

        ll = Max(ll, lr);
        ll++;

        dl = gbt_var_node_truncate((GBT_VARKEY*)DatumGetPointer(v->spl_ldatum), ll, tinfo);
        dr = gbt_var_node_truncate((GBT_VARKEY*)DatumGetPointer(v->spl_rdatum), ll, tinfo);
        v->spl_ldatum = PointerGetDatum(dl);
        v->spl_rdatum = PointerGetDatum(dr);
    }

    return v;
}

/*
 * The GiST consistent method
 */
bool gbt_var_consistent(GBT_VARKEY_R* key, const void* query, StrategyNumber strategy, Oid collation, bool is_leaf,
    const gbtree_vinfo* tinfo)
{
    bool retval = FALSE;

    switch (strategy) {
        case BTLessEqualStrategyNumber:
            if (is_leaf)
                retval = (*tinfo->f_ge)(query, key->lower, collation);
            else
                retval = (*tinfo->f_cmp)(query, key->lower, collation) >= 0 ||
                         gbt_var_node_pf_match(key, (const bytea*)query, tinfo);
            break;
        case BTLessStrategyNumber:
            if (is_leaf)
                retval = (*tinfo->f_gt)(query, key->lower, collation);
            else
                retval = (*tinfo->f_cmp)(query, key->lower, collation) >= 0 ||
                         gbt_var_node_pf_match(key, (const bytea*)query, tinfo);
            break;
        case BTEqualStrategyNumber:
            if (is_leaf)
                retval = (*tinfo->f_eq)(query, key->lower, collation);
            else
                retval = ((*tinfo->f_cmp)(key->lower, query, collation) <= 0 &&
                             (*tinfo->f_cmp)(query, key->upper, collation) <= 0) ||
                         gbt_var_node_pf_match(key, (const bytea*)query, tinfo);
            break;
        case BTGreaterStrategyNumber:
            if (is_leaf)
                retval = (*tinfo->f_lt)(query, key->upper, collation);
            else
                retval = (*tinfo->f_cmp)(query, key->upper, collation) <= 0 ||
                         gbt_var_node_pf_match(key, (const bytea*)query, tinfo);
            break;
        case BTGreaterEqualStrategyNumber:
            if (is_leaf)
                retval = (*tinfo->f_le)(query, key->upper, collation);
            else
                retval = (*tinfo->f_cmp)(query, key->upper, collation) <= 0 ||
                         gbt_var_node_pf_match(key, (const bytea*)query, tinfo);
            break;
        case BtreeGistNotEqualStrategyNumber:
            retval = !((*tinfo->f_eq)(query, key->lower, collation) && (*tinfo->f_eq)(query, key->upper, collation));
            break;
        default:
            retval = FALSE;
    }

    return retval;
}
